Preheat oven to 350F. Mix all ingredients together (a stand mixer makes short work of this, but you could also use a hand mixer), about 3-4 minutes. Mixture will be thick and form a ball (you may have to use your hands to get it all the way into a ball).Pat dough out on a cookie sheet (you can use parchment if you want) into a rectangle about ½ inch thick and about 6 inches wide, mounded a little in the middle. Bake at 350F for about 30 minutes, until a toothpick in the middle comes out clean. Slice on the diagonal, about ½-1 inch thick slices, directly on the cookie sheet (if you move the dough, it will crack). Turn the slices carefully onto their sides. Put the cookie sheet back in the oven and bake for another 10 minutes. Then turn the oven off and let the biscotti sit in the closed oven for at least 35 minutes, and then cool completely and dip in chocolate, if desired.